This invention relates to battery chargers, and particularly to battery chargers for transceivers having rechargeable batteries.
Portable transceivers are conventionally powered by a rechargeable battery which requires periodic recharging due to normal transceiver use, particularly due to the current drain on the battery from the RF power amplifier stages in the transmitter section of the transceiver. Conventionally the battery must be removed each time it is to be recharged. Unless a substitute battery is available, this approach renders the transceiver inoperable during the battery recharging period.
Several examples of battery chargers and charging techniques are shown in U.S. Pat. Nos. 4,290,002 to Piotti and 3,852,652 to Jasinski, and in Pawson, Ian, "Battery Charger for Portable Video," Television, January, 1980, Vol. 30, No. 3, pp. 142-3. Piotti discloses a method for controlling the recharging operation involving continual monitoring of the state of charge of the battery. Jasinski discloses a rapid battery charging system in which the battery charging rate is adjusted as a function of the rate of change of the internal temperature of the battery. The article by Pawson discloses a transformerless oscillator-driven DC-DC convertor for charging a 12-volt battery from a car battery.
Additional disclosures of possible relevance to this invention are found in U.S. Pat. Nos. 3,962,591 to Popka and 4,281,377 to Evans. Popka discloses a voltage doubler which uses only resistive, capacitive and semiconductive components. Evans discloses a power supply circuit which uses an operational amplifier oscillator, a buffer amplifier and a diode pump to derive a negative output voltage relative to the chassis ground of a vehicle from the vehicle battery.